/*

 * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package sun.net;

import java.net.SocketException;

import java.util.concurrent.atomic.AtomicInteger;

import sun.security.action.GetPropertyAction;

/**

 * Manages count of total number of UDP sockets and ensures

 * that exception is thrown if we try to create more than the

 * configured limit.

 *

 * This functionality could be put in NetHooks some time in future.

 */

public class ResourceManager {

    /* default maximum number of udp sockets per VM

     * when a security manager is enabled.

     * The default is 25 which is high enough to be useful

     * but low enough to be well below the maximum number

     * of port numbers actually available on all OSes

     * when multiplied by the maximum feasible number of VM processes

     * that could practically be spawned.

     */

    private static final int DEFAULT_MAX_SOCKETS = 25;

    private static final int maxSockets;

    private static final AtomicInteger numSockets;

    static {

        String prop = GetPropertyAction

                .privilegedGetProperty("sun.net.maxDatagramSockets");

        int defmax = DEFAULT_MAX_SOCKETS;

        try {

            if (prop != null) {

                defmax = Integer.parseInt(prop);

            }

        } catch (NumberFormatException e) {}

        maxSockets = defmax;

        numSockets = new AtomicInteger(0);

    }

    public static void beforeUdpCreate() throws SocketException {

        if (System.getSecurityManager() != null) {

            if (numSockets.incrementAndGet() > maxSockets) {

                numSockets.decrementAndGet();

                throw new SocketException("maximum number of DatagramSockets reached");

            }

        }

    }

    public static void afterUdpClose() {

        if (System.getSecurityManager() != null) {

            numSockets.decrementAndGet();

        }

    }

}